People don't realize they're 2 differently constructed bindings that offer 2 entirely different things. The highbacks on the 390's are softer laterally due to how they're milled out while the Formula's (2010) were designed to be stiffer on the outer and softer on the inner so when you drove into a carve you had support but when you jibbed it would give. Also 390's are 2 part construction with metal heel cups and plastic bases where as the formulas are a unibody construction. Toe straps are shaped different and designed for 2 different types of boots. The heel straps are also different as the 390's is softer and has gel in it while the formulas has plastic. But come 2011 everything I said just gets blown out of the water completely.